In machining a sintered metal and a cast iron, a sintered material including cubic boron nitride is frequently used as a cutting tool. For example, Japanese Patent Laying-Open No. 2016-074550 (Patent Document 1) discloses a sintered material that has chipping resistance improved by setting a content ratio of cubic boron nitride at less than or equal to 70 volume % and that is therefore suitable for machining of a centrifugal cast iron. Japanese Patent Laying-Open No. 2006-315898 (Patent Document 2) discloses a cubic boron nitride sintered material that has wear resistance improved by defining the thickness of a binder phase and that is therefore suitable for high-speed machining of a sintered metal and a cast iron.